Device for recognizing the position of the terminals of components

ABSTRACT

The device for recognizing the position of the terminals (A) of components (BE) whose optical unwanted structures proceed in two principal directions (X, Y) has an image transducer (BW) equipped with an objective (O); and at least one segmented ring light illumination (RB; RB1, RB2) whose rays (S; S1, S2) are incident onto the surface of the components (BE) from all sides upon exclusion of angular segments (WS) around the principal directions (X, Y). By suppressing the light directions incident perpendicular and parallel to the unwanted structures, the terminals (A) are presented with clearly higher contrast than the other structures of the components (BE). The device is particularly utilized in components vision systems of automatic equipping units. It enables a reliably recognition of the position of the spherical terminals even given flip chips, bare chips and ball grid arrays and, thus, an exact optoelectronic centering of these components.

BACKGROUND OF THE INVENTION

Vision technology is of critical significance for achieving a highequipping precision in the automatic equipping of substrates,particularly printed circuit boards or ceramic substrates, with SMDcomponents for surface mounting (SMD=Surface Mounted Devices). Thevision technology thereby comprises a substrate vision system and acomponents vision system. The substrate vision system acquires referencemarks or circuit structures of the substrate with a CCD camera. Acomputer determines the exact position of the substrate (X, Y, φ) and apotentially existing distortion from the position of the referencemarks. For equipping, all equipping positions (X, Y, φ) arecorrespondingly corrected.

The components vision system is composed of CCD camera, illumination andground glass screen. The corresponding components vision module isplaced on the offering table of the delivery modules. The equipping headplaces the components onto the ground glass screen such that theirterminals can be recognized. The positional deviation of the terminalsis determined, for example with a stored pattern, by optoelectroniccorrelation of all terminals. Using the values of the positionaldeviations, the automatic equipping unit corrects the equipping pathsand the rotational angle to the exact equipping position (X, Y, φ)previously determined with a substrate vision system.

The above-described optoelectronic centering of components with theassistance of a components vision system presents considerabledifficulties given some types of component, particularly given flipchips, bare chips and ball grid arrays. When the terminals whoseposition is to be recognized are viewed as useful structures and allother optically emerging structures of the components are viewed asunwanted structures, the unwanted structures are also at least partiallyclearly imaged. A reliable image evaluation is made more difficult orentirely prevented as a result thereof. Given, for example, flip chips,the aluminum interconnects, the silicon nitride structures and thesilicon oxide structures are to be cited as unwanted structures. Thebodies and edges of the components are also to be viewed as unwantedstructures.

European reference, A, 0 341 806 has disclosed a means for theinspection of printed circuit boards with SMD components that can bemoved across the printed circuit board. The means contains a cylindricalshaft in which two ring light illuminations lying above one another aswell as four cameras are arranged. The ring light illuminations are eachdivided into 4 segments whose middle regions lie in the principalcoordinate directions of the printed circuit board proceeding from thecenter. The cameras are likewise obliquely directed onto the printedcircuit board proceeding concentrically from the outside. Their middleaxes coincide with the coordinate directions.

The means serves the purpose of checking the presence and position ofthe components soldered on the printed circuit board. In particular, themeans is directed such onto the lateral edges of the component that thering light segment pointing in this direction and the camera allocatedto this are respectively activated. The means likewise serves thepurpose of determining the position of solder points on the printedcircuit board. This occurs by activating two of the segments lyingopposite the solder point and a camera directed perpendicular thereto.

SUMMARY OF THE INVENTION

The invention is based on the problem of creating a device forrecognizing the position of the terminals of components wherein theterminals to be recognized are optically isolated and disturbingstructure details are optically suppressed for simplification of theimage evaluation.

The invention is based on the perception that, given flip chips, barechips, ball grid arrays and comparable components with sphericalterminals, the optical unwanted structures proceed in two principaldirections, whereby these principal directions usually coincide with thedirections of the component edges. When, during the illumination, thelight directions incident parallel and perpendicular to the unwantedstructures are suppressed, then the terminals to be recognized in termsof their position are presented with clearly greater contrast than theunwanted structures.

Advantageous developments of the invention are as follows.

The development limits the precluded angle segments of the ring lightillumination to ±15°, so that the unwanted structures are imaged clearlymore weakly than the useful structures even given greater deliverytolerances of the components. Optimum conditions in view of an optimallyintense illumination of the useful structures derive according to claim3 when the precluded angle segments amount to approximately ±10°.

Given components with highly pronounced unwanted structures, a segmentedring light illumination is especially suitable, the rays thereof beingincident onto the surface of the components from all sides at anillumination angle of 45° to 90° relative to the optical axis of theobjective. Illumination angles of 55° to 65° are even better for theimaging of the spherical terminals of components with highly pronouncedunwanted structures, whereas optimum conditions for the imaging andpositional recognition of the terminals derive given an illuminationangle of approximately 60°.

The development enables a simple and economic realization of a ringlight illumination at a flat angle.

On the basis of a ring light illumination with illumination angles of15° to 45°, the development enables a high-intensity illumination of theterminals of components with weakly pronounced unwanted structures.Illumination angles of 25° to 35° are even better in this case, whereasoptimum conditions for a high-intensity imaging of the terminals ofcomponents with weakly pronounced unwanted structures derive given anillumination angle of approximately 30°.

The development enables a simple and economic realization of a ringlight illumination at a moderately steep angle.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention which are believed to be novel,are set forth with particularity in the appended claims. The invention,together with further objects and advantages, may best be understood byreference to the following description taken in conjunction with theaccompanying drawings, in the several Figures of which like referencenumerals identify like elements, and in which:

FIG. 1 depicts a component with spherical terminals and optical unwantedstructures proceeding in two principal directions, shown in plan view;

FIG. 2 depicts the schematic diagram of a segmented ring lightillumination for the component shown in FIG. 1;

FIG. 3 depicts a first modification of the schematic diagram shown inFIG. 2;

FIG. 4 depicts a second modification of the schematic diagram shown inFIG. 2; and

FIG. 5 depicts a device for recognizing the position of the terminals ofcomponents, shown in longitudinal section.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In a highly simplified, schematic illustration, FIG. 1 shows a plan viewonto a component BE whose spherical terminals arranged in the edgeregion are referenced A. Two principal directions X and Y proceedingperpendicular to one another and parallel to the component edges arealso indicated by arrows. Interconnects LBX proceeding in X-directionand interconnects LBY proceeding in Y-direction, each respectivelycomposed of aluminum, are also indicated in FIG. 1. Given a conventionalillumination of the surface of the component BE, these aluminuminterconnects LBX and LBY are clearly emphasized, i.e. they disturb arecognition of the position of the terminals a and are thus to beconsidered optical unwanted structures. The edges of the component BEare also a matter of optical unwanted structures. The body of thecomponent BE is likewise to be viewed as an unwanted structure since itssize can vary.

FIG. 2 shows the basic principle of a segmented ring light illuminationwith which the terminals A of the component BE can be optically isolatedand the optical unwanted structures can be at least largely suppressed.The ring light illumination referenced RB comprises a plurality oflight-emitting diodes LD arranged on a circle or on a polygon whose raysS would be obliquely incident onto the surface of the component BEarranged in the center from all sides without additional measures. Itcan be seen, however, that the rays S of the ring light illumination RBare suppressed in the region of angular segments WS around the principaldirections X and Y. Delivery tolerances of the components BE are takeninto consideration in that it is not only the principal directions X andY themselves but regions of ±10° around the principal directions X and Ythat are excluded from the illumination.

What the angular segments WS effect is that the light directions of thering light illumination RB incident parallel and perpendicular to theoptical unwanted structures are suppressed, and that, asa a result, theterminals A important for an optoelectronic centering of the componentsBE are presented with clearly higher contrast than the optical unwantedstructures.

Given the principle shown in FIG. 2, an incidence of the rays S of thering light illumination RB onto the surface of the component BE is alsosuppressed in the region of the principal directions X and Y by theoccluding effect of the angular segments WS. According to FIG. 3, thesame effect can also be achieved in that the light-emitting diodes areeliminated in the segments of the ring light illumination to correspondto the angular segments WS.

According to FIG. 4, the effect of the ring light illumination RBdesired for the suppression of unwanted structures can also be achievedin that the light-emitting diodes LD in the segment regions SBcorresponding to the angular segments WS are not activated. Thisarrangement has the advantage that the light-emitting diodes LD in thesegment regions SB can be added in for increasing intensity givencomponents BE with less strongly pronounced unwanted structures.

In a highly simplified schematic illustration, FIG. 5 shows a device forrecognizing the position of the terminals A of components BE inlongitudinal section. With, for example, the suction pipette (not shownin greater detail in FIG. 5) of an equipping head, the components BE arethereby brought into the position required for recognizing the positionof the terminals A. In this position, the components BE are centrallyaligned relative to the optical axis OA of an objective that images theterminals A onto the light-sensitive surface of an image transducer BW.For example, the image transducer BW is a matter of a CCD camera of thetype Sony XC75C with 484 effective rows and 746 effective columns.

A first ring light illumination RB1 and a second ring light illuminationRB2, which can both be separately activated and deactivated, areprovided for illuminating the surface of a component BE.

The first ring light illumination RB1 comprises a plurality oflight-emitting diodes LD1 that, according to the principle shown in FIG.4, are arranged on a circle concentric with the optical axis OA. Therays S1 emanating from the light-emitting diodes are steered onto thesurface of the component BE via an annular mirror SP that is alignedcoaxially with the optical axis OA, whereby the illumination anglemeasured toward the optical axis OA is a α1=60°.

The first ring light illumination RB1 is utilized for the illuminationof components BE with highly pronounced unwanted structures,whereby--according to the pattern shown in FIG. 4--segment regions SB of±10° around the principal directions X and Y are not activated. Thesegment regions SB, however, can be activated as auxiliary illuminationfor increasing the intensity given components BE with less highlypronounced unwanted structures.

The second ring light illumination RB2 comprises a plurality oflight-emitting diodes LD2 that--according to the principle shown in FIG.3--are arranged on a circle concentric with the optical axis OA. Therays S emanating from the light-emitting diodes LD2 are directeddirectly onto the surface of the component BE, whereby the illuminationangle measured toward the optical axis OA is α2=30°.

The second ring light illumination RB2 is utilized for thehigh-intensity illumination of components BE with weak unwantedstructures, whereby--according to the pattern shown in FIG. 3--angularsegments of ±14° around the principal directions X and Y are excludedfrom the illumination for suppressing unwanted structures.

For example, light-emitting diodes HLMP8103 Type T that emit red lightwith a wavelength of 637 nm are utilized for the first ring lightillumination RB1 and the second ring light illumination RB2.

The device shown in FIG. 5 is utilized in automatic equipping units forcomponents vision systems. In particular, it is suitable for reliablyrecognizing the position of the spherical terminals of components.

The invention is not limited to the particular details of the apparatusdepicted and other modifications and applications are contemplated.Certain other changes may be made in the above described apparatuswithout departing from the true spirit and scope of the invention hereininvolved. It is intended, therefore, that the subject matter in theabove depiction shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A device for recognizing a position of terminalsof components, comprising:the components having optically disturbingsurface structures at terminal sides thereof that proceed in twoprincipal directions residing perpendicular to one another that proceedparallel to lateral edges of a component; the components being placeablein an active region of the device: an image transducer having anobjective and at least one segmented ring light illumination: theobjective having an optical axis that proceeds at least approximatelythrough a center of the ring light illumination: the objective and thering light illumination arranged above a location provided for thecomponents; and the respective component being placeable relative to thering light illumination at least approximately centrally in an angularposition wherein rays of the ring light illumination upon exclusion ofangular segments lying in a region of the principal directions, aredirected obliquely onto the surface of the components from all sides ofthe components.
 2. The device according to claim 1, the excluded angularsegments of the ring light illumination lie in an angular rangedeviating -15° through +15° from the principal directions.
 3. The deviceaccording to claim 1, the excluded angular segments of the ring lightillumination lie in an angular range deviating approximately ±10° fromthe principal directions.
 4. The device according to claim 1, whereinthe rays of the segmented ring light illumination are directed onto thesurface of the components at an illumination angle of 45 to 90° relativeto an optical axis of the objective.
 5. The device according to claim 4,wherein the segmented ring light illumination, comprises:light-emittingdiodes that, upon exclusion of the angular segments, are arranged bysectors on a circle or polygon coaxial with the optical axis of theobjective; and a segmented ring light illumination having an annular orpolygonal mirror arranged coaxially with the optical axis of theobjective that steers rays emitted by the light-emitting diodesobliquely onto the surface of the components.
 6. The device according toclaim 1, wherein the rays of the segmented ring light illumination aredirected onto the surface of the components at an illumination angle of55 to 65° relative to an optical axis of the objective.
 7. The deviceaccording to claim 6, wherein the segmented ring light illumination,comprises:light-emitting diodes that, upon exclusion of the angularsegments, are arranged by sectors on a circle or polygon coaxial withthe optical axis of the objective; and a segmented ring lightillumination having an annular or polygonal mirror arranged coaxiallywith the optical axis of the objective that steers rays emitted by thelight-emitting diodes obliquely onto the surface of the components. 8.The device according to claim 1, wherein the rays of the segmented ringlight illumination are directed onto the surface of the components at anillumination angle of approximately 60° relative to an optical axis ofthe objective.
 9. The device according to claim 6, wherein the segmentedring light illumination comprises:light-emitting diodes that, uponexclusion of the angular segments, are arranged by sectors on a circleor polygon coaxial with the optical axis of the objective; and asegmented ring light illumination having an annular or polygonal mirrorarranged coaxially with the optical axis of the objective that steersrays emitted by the light-emitting diodes obliquely onto the surface ofthe components.
 10. The device according to claim 1, wherein the devicefurther comprises a second segmented ring light illumination that isseparately activatable, the second segmented ring light illuminationhaving rays incident onto the surface of the components at anillumination angle of 15 to 45° relative to the optical axis of theobjective.
 11. A device for recognizing a position of terminals ofcomponents, comprising:the components having optically disturbingsurface structures at terminal sides thereof that proceed in twoprincipal directions residing perpendicular to one another that proceedparallel to lateral edges of a component: the components being placeablein an active region of the device: an image transducer having anobjective and at least one segmented ring light illumination: theobjective having an optical axis that proceeds at least approximatelythrough a center of the ring light illumination: the objective and thering light illumination arranged above a location provided for thecomponents: and the respective component being placeable relative to thering light illumination at least approximately centrally in an angularposition wherein rays of the ring light illumination upon exclusion ofangular segments lying in a region of the principal directions, aredirected obliquely onto the surface of the components from all sides ofthe components, a second segmented ring light illumination that isseparately activatable, the second segmented ring light illuminationhaving rays incident onto the surface of the components at anillumination angle of 25 to 35° relative to the optical axis of theobjective.
 12. The device according to claim 11, wherein the secondsegmented ring light illumination has light-emitting diodes that, uponexclusion of the angular segments, are arranged by sectors on a circleor polygon coaxial with the optical axis of the objective.
 13. A devicefor recognizing a position of terminals of components, comprising:thecomponents having optically disturbing surface structures at terminalsides thereof that proceed in two principal directions residingperpendicular to one another that proceed parallel to lateral edges of acomponent: the components being placeable in an active region of thedevice: an image transducer having an objective and at least onesegmented ring light illumination: the objective having an optical axisthat proceeds at least approximately through a center of the ring lightillumination: the objective and the ring light illumination arrangedabove a location provided for the components: and the respectivecomponent being placeable relative to the ring light illumination atleast approximately centrally in an angular position wherein rays of thering light illumination upon exclusion of angular segments lying in aregion of the principal directions, are directed obliquely onto thesurface of the components from all sides of the components, a secondsegmented ring light illumination that is separately activatable, thesecond segmented ring light illumination having rays are incident ontothe surface of the components at an illumination angle of approximately30° relative to the optical axis of the objective.
 14. The deviceaccording to claim 10, wherein the second segmented ring lightillumination has light-emitting diodes that, upon exclusion of theangular segments, are arranged by sectors on a circle or polygon coaxialwith the optical axis of the objective.
 15. A device for recognizing aposition of terminals of components, comprising:the components havingoptically disturbing surface structures at terminal sides thereof thatproceed in two principal directions residing perpendicular to oneanother that proceed parallel to lateral edges of a component: thecomponents being placeable in an active region of the device: an imagetransducer having an objective and at least one segmented ring lightillumination: the objective having an optical axis that proceeds atleast approximately through a center of the ring light illumination: theobjective and the ring light illumination arranged above a locationprovided for the component: and the respective component being placeablerelative to the ring light illumination at least approximately centrallyin an ancular position wherein rays of the ring light illumination uponexclusion of angular segments lying in a region of the principaldirections, are directed obliquely onto the surface of the componentsfrom all sides of the components, a second segmented ring lightillumination that is separately activatable, the second segmented ringlight illumination having rays incident onto the surface of thecomponents at an illumination angle of 15 to 45° relative to the opticalaxis of the objective: the second segmented ring light illuminationhaving light-emitting diodes that, upon exclusion of the angularsegments, are arranged by sectors on a circle or polygon coaxial withthe optical axis of the objective.